Heat-drawing furnace



June 25, 1929. E. F.-DAV|S HEAT DRAWING FURNACE Filed June 16, 1926 2 Sheets-Sheet 1 IN VEN TOR. Erna: t F. D a 1/15,

W 7 ATTORNEYS June 25, 1929. E. F; DAVIS HEAT DRAWING FURNACE Filed June 16, 1926 2 Sheets-Sheet 2 INVEINTORJ Ernest 1 Dana,

BY -%W(rM A TTORNEYS Patented June 25, 1929.

UNITED STATES PATENT OFFICE.

ERNEST F. DAVIS, OF MUNCIE, INDIANA, ASSIGNOR TO WARNER GEAR COMIANY, OF MUNOIE, INDIANA, A CORPORATION" OF INDIANA.

HEAT-DRAWING FURNACE.

Application filed June 16,

My invention relates to furnaces and particularly that type oil furnace for heat treating wherein the articles to be treated are im HlQIfSCCl in a bath of oil. The invention 1s particularly applicable to furnaces tor heat treating hardened work such as steel. gears and the like for drawing the temper thereof by immersing the same in a bath of heated Oil in the manner commercially known as oil drawing.

It is one of the objects of my invention to provide a furnace of the above type wherein the mechanical handling of the articles may be .reduced to a minimum and wherein the uncertainty oi the time element in drawing the temper of hardened work may be eliminated.

1n the drawings illustrating certain embodiments of my invention.

Fig. 1 is a side elevation. partly in section of a furnace embodying my invention;

Fig. 2 is a plan view of another form of furnace embodying my invention, and

Fig. 3 is a longitudinal sectional. view thereof.

In the embodiment illustrated in Fig. 1 I provide a cylindrical open topped oil tank 1 which is adapted to be surrounded by suit able insulating material 2 in turn surrounded and covered by a metallic cover or easing 3. This tank at its top edge is provided with a hollow sill 41 having an internal skirt 5 which projects down into the tank slightly below the oil level. The tank is adapted to be tilled. with oil to about the level indicated in. which the material to be treated is adapted to be innnersed. This oil is maintained at a pro per temperature by controllable heating units 6 of a type well known in the commercial a rt, which units are supported on the sides of the tank at suitable intervals, being arranged more closely together at the entry point in the tank, that is, at the point where the cold articles are introduced. These heating units are connected by suitable circuits 7 with. the instruments of control 8 by which the supply of current may be readily varied either manually or automatically through the medium of automatic thermostats in a manner well hooks 11 or cpruringe 3.2.. l c hooks or p 1926. Serial N0. 116,300.

an extension 18 provided at its lower end with a propeller or agitator 19 by which during the rotation. of the bull wheel the oil is suliiciently agitated or circulated past the heaters in order to maintain an even temperature oi? the oil throughout its mass. A. suitaliile casing or cover 20 closes the top of the tank which casing is provided with an opening 9.1 to permitthe insertion and removal of the articles to be immersed.

The agitation. of the oil not only causes a circulation of the same past the heating units to thereby maintain an even temperature thro rout the n'iass but also assists in preventi g the accumulation of sludge and carbon on the heating units, which accumulation would reduce the eiliciency oi? the units. Furthermore, by. hangin of the heating units on the sides oi the tank instead of placing them in the bottom UTE the tank, the sludge and carbon will be precipitated. away from the units instead of on them as would be the case if they were located in the bottom of the tank. The hanging of theunits 011 the side of the tank permits a more ready removal oi" the units for cleaning and inspection than it they were placed. in the bottom of the tank.

In the structure illustrated in Figs. 2 and 3 I have shown another form of furnace which may be used advantageously. In this form I preferably provide an elongated tank 22 surrormded by suitable insulation 23 covered by an enclosing casing 24. This tank is likewise provided with the heating units 6 having the control circuit 7 connecting the same with the controlling instrument board 8 as is the case in the structure illustrated in Fig. 1.

F or immersing the materials to be treated in. an oil bath I provide a conveyor 25 preterably of the chain type in the form of a continous belt and provided at suitably spaced intervals with agitating paddles or projections 26. This conveyor travels over an idler spmeltet or pulley 27 on a slzurtt cl l 1. ll

fm'ersed in the oil'of the tank. The paddles or -projections 26 serve to agitate the oil for the same purpose as that of the agitator 19 in the structure illustrated in Fig. 1.

While I have spoken of the liquid in the tank as being oil it will be understood that any other suitable material for the purpose v may be used and where I have referred in the specification and claims to oil it will be understood that this term is sufficiently comprehensive to include other liquids which may be used for similar purpose.

I claim as my invention: 1. In an oil drawing furnace the combina tion with a tank constructed to contain oil and surrounded by insulating material, of controllable electrlc heating un1ts arranged in 7 said tank and immersed in the oil for heating said oil, progressively moving carrier means for supportlng the work immersed in said 011 and progressively moving the same through the tank and means for imparting a circulatory movement to the oil to cause the same to circulate over the heating units.

2. In an oil drawing furnace the combination with a tank constructed to contain oil and surrounded by insulating material, of

controllable electric heating units supported against the sides of the tank immersed in the oil for heating said oil, progressively moving carrier means for supporting the work immersed in said oil and progressively moving the same through the tank and means for imparting a circulatory movement to the oil to cause the same to circulate over the heating units.

3. In an oil d 'awing furnace the combination with a circular tank constructed to contain oil and surrounded by insulating material, a wheel mounted above said tank to retate in a horizontal plane, means for supporting the work to be treated from said wheel immersed in the oil in the tank, (ontrollable heating units arranged in said tank and immersed in the oil and means for imparting a circulatory movement -to the oil to cause the same to circulate past the heating units.

4. In an oil drawing furnace the combination with a circular tank constructed to contain oil and surrounded by insulating material, of a wheel mounted above said tank and rotating in a horizontal plane, means for supporting work from said wheel immersed in the oil in the tank, controllable heating units supported on the sides of said tank and means for imparting a circulatory movement to the oil in the tank to cause the same to circulate past the heating units.

In witness whereof, I, ERNEST F. DAVIS, have hereunto set my hand at Muncie, Indiana, A. D. one thousand nine hundred and twenty-six.

ERNEST F. DAVIS. 

